The Blur 4X lives in some conceptual netherworld at the end of the Blur family tree, sort of like a Platypus, except with sharp teeth and the ability to both swim and fly real fast. It's slacker, longer and lower than its brethren, and employs heavily gusseted top and down tubes that are much larger and thicker than even the Blur LT, making it able to handle everything from jumping to slopestyle stunts.

The end product is an overbuilt frame designed for a life of abuse, forming the basis of a rock-stable bike that can stick the ugliest lines as well as carve turns between gates with total conviction. For a bike to tackle sketchy terrain without investing in the extra weight and wallow of super-long travel rigs, the 4X is the perfect Platypus.

Yep, I was going to say Banshee Phantom and Kona Process 111 as well.
Some people I know have shortened the Salsa Horsethief to achieve this too.

(I'm not sure than the ethos of the Blur 4x works on a 29er though - they just aren't going to be as chuckable. I rode a Phantom and can say that it was about as chuckable as I can imagine a 29er ever being though)

I rode a Blur 4X for a few years and switched to a Tallboy (aluminum one) with a 1.5 degree angleset and a 120mmish fork. So it's not stock, and 29ers do feel different to 26ers... so maybe that's not helpful. However, it does do that "corner-smashing" thing a lot like I remember on the 4X, even though the BB isn't all that low and the HA still isn't all that slack. People speculate that the big BB drop on a 29er compared with a 26er gives it that low-BB feel. The slackened Tallboy is certainly very fun bike short-travel bike.

I also ride a Rune 26er which has that long, low, feel that Banshee aim for... not unlike the 4X, but feels longer - probably because it is. That Phantom looks really promising.

I wouldn't worry about a Phantom feeling heavy on long rides - my Spitfire 27.5 is a fairly hefty low carbon enduro gnarpoon build and I'd still rather do 100 miles of the South Downs Way on it than my Cotic Soul. It only feels heavy when lifting it over stiles or into the car but otherwise it's a rocketship!*

(I'm not sure than the ethos of the Blur 4x works on a 29er though - they just aren't going to be as chuckable. I rode a Phantom and can say that it was about as chuckable as I can imagine a 29er ever being though)

I can vouch that the Banshee Phantom is chuckable, certainly more so than the Heckler I had before. I only realised recently that the wheelbase is actually shorter than a Spitfire with 650b wheels size for size. Plus it doesn't have the floppy fork feeling that comes with slack 26/650b bikes.

Mine is set up with MRP Stage forks and Flow Ex / Rubber Queen 2.2 (loads of tyre clearance) and rides beautifully. 105mm rear, 130mm front. It is exactly the bike I wanted it to be: playful down and off things, big wheeler monster truck over chossy ground, nimble through the corners and a highly accomplished climber. It is also the first bike I've been able to manual properly since I rode a BMX!

No idea about weight though, although I suspect it is sub 30 lb based on how much easier it is to lift compared to my 31 lb heckler. With any 29er the first place to save weight is the wheels so if you can go carbon or Arch Ex size rims that would be most of the battle done. I don't have any problem pedaling it about though, even on long rides, the suspension works incredibly well and is such short travel anyway that you are never fighting it up a hill. I suspect the Kona is similar and is probably a lot down to how 29er wheels "work".

They should be landing in the UK at the end of the month (I got one early because I'm special.......and made enough of a pain in the arse of myself to Pedals Cycles in Edinburgh).

At the moment I suspect the Phantom or Process 111 are the only bikes that come close to your wishes. Not sure if the Orange Segment does anything for you, on paper it is similar to either of the other bikes. They are never going to ride in the same manner as a Blur TRc/4x, as they have bigger wheels and therefore require a different riding style, but they are certainly from the same school of thought.

If anyone who lives near Dundee fancys a go they are more than welcome to try it out (mine is large, Pedals in Edinburgh have a medium demo bike). Apologies to those that care about these things for having it in the granny ring for the photo. The shock is also on the other way round now.

@ AlexSimon - what were your overall impressions of the Phantom? I'm considering onebut worry it's too heavy for an all-rounder that I'll want to long days on as well as rock tech.

I rode all the Banshee full sussers on the same day. Around the same loop.
They're all on the heavy side, but then as soon as you put aggressive geometry on a short travel bike, you've got to build it so that it will take a bit of stick. It's a tricky one.
The Phantom was great, but it was also the bike that made me decide that 29ers weren't for me. This was because it was the most agile of the 29ers I've tried, yet still not as much fun for me personally as a 650b/26. Probably faster, and maybe even more fun in a straight line, but just not as much fun around corners and swapping lines.

I'm just not sure I'm ever going to feel like I'm on top of the steering on a 29er.
The rear end of the phantom was great though - felt a lot more than the 105mm and all the Banshees pedalled well. In fact they all pedalled so well that I found myself leaning towards the Rune and Prime more than the Spitfire and Phantom. Back at home, on paper, the weight seems an issue, but on a short tight, techy trail centre loop, it just didn't matter.

I agree with a lot of what you say but I guess it depends on where you ride. Most of my riding is big, open moorland style trails in Scotland where it absolutely rocks. Not so much winding through trees. If it was tightly wooded twisty singletrack I suspect my opinions of the Phantom would be different, but probably due to wheel mass and acceleration rather than geometry (but then the Spitfire I tried didn't feel great in those situations either, and that was the geometry effects due to the head angle). It also isn't the bike I would choose if most of my riding involved styling it up off tabletops.

If "nimble" really is top of the list of qualities then the Process 111 is probably going to be slightly better than the Phantom due to the CS length, but there isn't much in it (~7.5mm I think) and I guess you lose out in other quarters such as stability and climbing prowess.

I guess I have also spent 5 years riding a 29er hardtail (Swift) so had learnt how to handle a 29er. I'm also a broad, monkey armed, long legged 6ft which I suspect helps with handlebar wrestling.

I'm not as convinced by the 111's suspension as I am by its geometry - not much anti-squat so pedalling efficiency is lower, high anti-rise so it gets stiffer under braking and not much linkage progression so it'll bottom out more easily. With a great shock and tune you can deal with most of that fairly well but not as well as with a good shock and better linkage kinematics. Phantom should pedal better, brake better and cope better with big hits.

Saying that the Process models all look awesome fun but I think all need careful shock selection and tuning!